Method of producing pipes with internal helical fins

ABSTRACT

A pipe blank with internal longitudinal fins is subjected to drawing and concurrent rotation so as to alter the shape of its cross-section in the course of rotation to prevent the pipe blank from slipping in relation to the drawhole. The operations result in producing the pipe with internal fins in the form of a helix. Next, the pipe produced thereof is drawn additionally to give it the requisite shape. The herein-described method is suitable for the production of pipes with internal helical fins having practically any height required.

United States Patent 1 1 Starostin et a1.

[ 1 July 23, 1974 METHOD OF PRODUCING PIPES WITH INTERNAL HELICAL FINS [76] Inventors: Jury Stepanovich Starostin, ulitsa Filed:

Krashykn Kommunarov, 6, kv. 36;

Viktor Ivanovich Plokhov, ulitsa Stroitelei, 20, kv. 75; Veniamin Kuzmich Erokhov, ulitsa Svobody, 230, kv. 62; Vladimir Prokopievich Ivanov, prospekt Metallurgov, 60, kv. 55, all of Kuibyshev; Vladimir Nikolaevich Krotkov, ulitsa Chkalova, 24/32, kv. 132, Moscow; Albert Viktorovich Anisimov, Novo-Mytischinsky prospekt, 23/7, kv. 102, Mytischi Moskovskoi olgla sth 'Rustem Nurievich Ajupov, ulitsa Gvardeiskaya, 26, kv. 103 Mikhail Fedotovich Golovinov, ulitsa Pugachevskaya, 59, kv. 16, both of Kuibyshev, all of USSR.

Jan. 15, 1973 Appl. No.: 323,404

us. C1. g 72/285, 72/367 Int. Cl. B21c 3/12 Field of Search 72/283, 285, 370, 467,

72/276, 278, 299, 64, 367; 113/118 A; 29/157.3 R, 157.3 A, 157.3 AH

[56] References Cited UNITED STATES PATENTS 299,285 5/1894 Spruce 72/64 1,967,487 7/1934 Waisner.. 72/64 2,270,398 l/l942 Westin 72/283 2,852,835 9/1958 Harvey et al 72/283 3,289,451 12/1966 Koch et al 72/283 3,422,518 l/l969 French 72/283 3,517,536 6/1970 Fitzmaurice 72/275 3,566,651 3/1971 Tlaker 72/370 Primary Examiner-Charles W. Lanham Assistant ExaminerM. J. Keenan Attorney, Agent, or Firm-Holman & Stern 5 7] ABSTRACT A pipe blank with internal longitudinal fins is subjected to drawing and concurrent rotation so as to alter the shape of its cross-section in the course of rotation to prevent the pipe blank from slipping in relation to the drawhole. The operations result in producing the pipe with internal fins in the form of a helix. Next, the pipe produced thereof is drawn additionally to give it the requisite shape. The herein-described method is suitable for the production of pipes with internal helical fins having practically any height required.

1 Claim, 5 Drawing Figures METHOD OF PRODUCING PIPES WITH INTERNAL HELICAL FINS BACKGROUND OF THE INVENTION The present invention relates generally to metal shaping processes and more particularly, it relates to methods of producing pipes with internal helical fins by way of drawing and concurrent rotation.

A method of fabricating pipes with internal helical fins is known in the art wherein a thick-walled pipe blank with plain internal surface is subject to drawing on a mandrel and concurrent rotation.

With the above method, the mandrel is fitted with helical slots whose number is in agreement with that of the fins to be obtained. a

Due to the pressure created during the drawing operation, blank metal fills the slots in the mandrel forming helical internal fins. v i

This process is adaptable for producing pipes that do not have high internal fins, insofar as fairly large frictional forces arising between the slot and metal surfaces impede filling the mandrel slots with metal.

BRIEF DESCRIPTION OF THE DRAWINGS It is an object of the prevent invention to provide a method of producing pipes with helical internal fins which would make it possible to obtain pipes with internal helical fins of any height required, up to that approaching the pipe nading.

Said and other objects of the invention are accoplished by the provision of a method of producing pipes with internal helical fins wherein the drawing of a pipe blank is performed concurrently with its rotation, in which method, according to the invention, the pipe blank fitted with longitudinal internal finsis subject to drawing and concurrent rotation so as to change the shape of its cross-section to avoid slippage of the blank in relation to a drawhole in the course of rotation which results in obtaining the pipe with spiral-shaped internal fins, whereupon the pipe with the internal helical fins produced is drawn further to impart the requisite shape to its cross-section.

The method realized according to the proposed invention enables the production of the pipes with internal helical fins having practically any height. required, up to that approaching to the pipe radius, and any wall and fin thickness but not less than 1.0 mm.

Quality of the internal surface of the pipes produced by the herein-proposed method is as high as before and does not differ from that of the pipe blank.

The invention will now be explained in greater detail with reference to an exemplary embodiment thereof, which is represented in the accompanying drawings, wherein:

FIG. 1 shows diagrammatically mutual arrangement of a pipe blankpipe and drawholes for accomplishing the method according to the invention;

FIG. 2 is a section view taken along the line II II of FIG. 1;

FIG. 3 is a section view taken along the line III III of FIG. 1;

FIG. 4 is a fragmentary section view taken along the line IV IV of FIG. 1 and;

FIG. 5 is a section view taken along the line V V of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A round pipe blank 1 (FIGS. 1, 2) with longitudinal internal fins 2 is subject to deformation in the drawhole 3 of a drawing machine (not shown in the drawing). The drawhole is connected with a drive (not shown in the drawing) adapted for its rotation in the course of drawing through a worm gear 4. In order to prevent the pipe blank 1 from slipping relative to the drawhole 3 when the latter is being rotated, an outlet section of the drawhole 3 is oval in shape.

The outlet section of the drawhole may have any other shape ensuring its rotation in conjunction with the pipe blank.

Due to the strains that are liable to be incurred to the pipe blank 1 duringdrawing andtwisting the blank takes the shape of an oval pipe 5, as shown in FIG. 3, its internal fins 6 being arranged along a helix in relation to the longitudinal axis 7.

As a result of the twisting process effected in the oval drawhole 3 the exterior of the pipe 5 assumes the shape of a helical surface, each subsequent in the direction of drawing section of the surface being turned at a certain angle in relation to the previous one.

FIGS. 3 and 4 show the pipe sections one of which is turned in relation to another at an angle of C.

y In order to impart a circular shape to the exterior of the pipe 5, the pipe is passed through an additional drawhole 8 with a circular outlet.

Deformation of the pipe 5 in the drawhole 8 results in producing the pipe 5 (FIG. 5) with a circular crosssection and internal fins 10 arranged along a helix in relation to the longitudinal axis 7.

The additional drawhole can be made with .an outlet of any required shape to suit the requirements on the pipes produced.

Pipes with variable fin pitch and angle of inclination of the helix are obtainable by adjusting both the speed of drawing and rotation. Moreover, the pipes fabricated can have fin helices twisted counterclockwise and clockwise on the alternate sections of the pipe.

The pipes in trial lots produced by the method described hereinbefore were up to 6 mm. in outer diameter.

It is to be understood that the method of the invention is in no way limited by the exemplary embodiment disclosed herewith and various modifications can be resorted to by those skilled in the art, such as fall within the true spirit and scope of the following Claims.

What we claim is: 1. A method of producing a pipe of required crosssectional shape from a pipe blank with internal fins on a drawing machine having a rotatable draw hole, the method comprising the steps of:

drawing and concurrently rotating the pipe blank through the draw hole of the drawing machine; altering the cross-sectional shape of the pipe blank in said draw-hole simultaneously therewith, to prevent slippage between the draw hole and the pipe blank andproduce a drawn section thereof;

additionally drawing the drawn section to produce said pipe of required cross-sectional shape with said internal fins. 

1. A method of producing a pipe of required cross-sectional shape from a pipe blank with internal fins on a drawing machine having a rotatable draw hole, the method comprising the steps of: drawing and concurrently rotating the pipe blank through the draw hole of the drawing machine; altering the cross-sectional shape of the pipe blank in said draw-hole simultaneously therewith, to prevent slippage between the draw hole and the pipe blank and produce a drawn section thereof; additionally drawing the drawn section to produce said pipe of required cross-sectional shape with said internal fins. 